1. Field of the Invention
The present invention is related to a module for transferring a substrate. More particularly, the present invention is related to a module for transferring a substrate between a container to receive a plurality of substrates and a module for processing the substrate.
2. Description of the Related Art
Generally, semiconductor devices are manufactured through a three-step process. First, a fabrication process is performed for forming electronic circuits on a silicon wafer used as a semiconductor substrate. Second, an electrical die sorting (EDS) process is performed for inspecting electrical characteristics of the semiconductor devices on the semiconductor substrate. Third, a packaging process is performed for packaging the semiconductor devices in epoxy resins and individuating the semiconductor devices.
The fabrication process may include a deposition process for depositing a layer on the substrate, a chemical mechanical polishing (CMP) process for planarizing a surface of the layer, a photolithography process for forming a photoresist pattern on the layer, an etching process for an electrical pattern using the photoresist pattern, an ion implantation process for implanting predetermined ions into predetermined portions of the substrate, a cleaning process for removing impurities from the substrate, an inspection process for inspecting the surface of the substrate on which the layer or the pattern is formed, or other similar processes.
These processes are performed under a high vacuum condition in order to prevent contamination of the semiconductor substrate. To provide the high vacuum condition, a substrate process apparatus includes a load lock chamber maintained under a low vacuum condition, a process chamber in which the process is performed, and a substrate transfer chamber for transferring the semiconductor substrate between the load lock chamber and the process chamber.
Recently, a substrate process apparatus for some processes (for example, a deposition process or a dry etching process) on a 300 mm semiconductor substrate includes a substrate process module, a substrate transfer module and a load lock chamber. The substrate transfer module includes a load port for supporting a front opening unified pod (FOUP), a substrate transfer chamber disposed between the load port and the load lock chamber, and a substrate transfer robot for transferring the semiconductor substrate between the FOUP and the load lock chamber.
A fan filter unit (FFU) is connected to an upper portion of the substrate transfer chamber. The fan filter unit supplies an interior of the substrate transfer chamber with clean air for preventing contamination of the semiconductor substrate being transferred by the substrate transfer robot.
A plurality of exhaust holes is formed through a bottom panel of the substrate transfer chamber in order to exhaust the clean air supplied from the fan filter unit out of the substrate transfer chamber or to a clean room in which the substrate process apparatus is provided.
When an internal pressure of the substrate transfer chamber is lower than a pressure of the clean room, the air in the clean room may flow back into the substrate transfer chamber, so that the semiconductor substrates received in the FOUP and the semiconductor substrate being transferred by the substrate transfer robot may be contaminated. Therefore, it is preferable to maintain the internal pressure of the substrate transfer chamber higher than the pressure of the clean room. The pressure of the clean room, in which the substrate process apparatus is provided, is generally a positive pressure (i.e., higher than atmospheric pressure).
For example, a multichamber processing system including a container-housing chamber, a cleaning chamber and a load lock chamber is disclosed in the prior art. The cleaning chamber has an inlet line for introducing a clean gas into the cleaning chamber and a pressure control device for controlling the pressure in the cleaning chamber. The pressure control device includes a valve for adjusting a flow rate of the gas in the inlet line, a differential pressure gauge for detecting a differential pressure between the pressure in the cleaning chamber and the atmospheric pressure, and a valve controller for adjusting an opening degree of the valve so that the pressure in the cleaning chamber is maintained at the positive pressure based on a result of the detecting by the differential pressure gauge.
In addition, wafer atmospheric transport module having a controlled mini-environment is disclosed in the prior art. According to this example, a blower located in the top region of an enclosed housing is configured to generate a flow of air downward. The airflow generated by the blower is restricted from freely flowing through a perforated sheet and is partially induced to be redirected toward the shelf, and a cassette having one or more wafers is configured to sit on a shelf in the enclosed housing and thus be subjected to the redirected air flow.
The fan filter unit includes a fan for supplying external air into the substrate transfer chamber and a filter for removing particles contained in the external air being supplied into the substrate transfer chamber. However, the filter cannot remove airborne molecular contaminants, such as organic contaminants, contained in the external air being supplied into the substrate transfer chamber. Such airborne molecular contaminants may cause various defects on the semiconductor substrate.
Examples of the defects may include a variation of a critical dimension (CD) of a photochemical amplified resist pattern and T-top defect caused by ammonia, a natural oxide layer generated by ozone, condensational contaminants or the like. Variation of the critical dimension of the photochemical amplified resist pattern and T-top defect may be detected in the fabrication process, and operation failure of electrical circuit elements such as transistors due to organic contaminants such as dioctyl phthalate (DOP) may be detected in the electrical die sorting process.